1. Field of the Invention
The present invention relates principally to the production of heavy oil or a selected mineral from subsurface crude oil bearing formations. More particularly, the present invention concerns a heavy crude oil production system and method employing steam injection into a plurality of lateral or radial injection passages extending from a like plurality of openings formed in the casing or primary wellbore or extending from an interval of the wellbore and into the formation after a section of well casing has been removed. The present invention also involves the production of formation fluid from a plurality of lateral or radial production passages that also extend from the wellbore and are in spaced relation with the injection passages. The scope of the present invention also concerns a method and apparatus for production of a wide variety of subsurface minerals from a subsurface earth formation, other than heavy crude oil, by means of chemical leaching, with or without steam injection.
2. Description of the Prior Art
The term “bores”, as used herein, is employed to describe a plurality of lateral passages that extend from a wellbore into a subsurface earth formation of interest. It is not intended that this term be restricted solely to a rotary boring or drilling operation. Rather, it is intended that the terms “lateral or radial bores” and “lateral or radial passages” be considered synonymous. The term “bore” is intended to encompass any method of forming a passage in an earth formation extending laterally or radially from a wellbore. For example, lateral or radial passages are presently formed in subsurface earth formations by radial drilling, motor drilling or by hydraulic means such as hydraulic jet blasting or drilling. The terms “lateral” or “radial” are intended to identify passages that extend from a wellbore into an earth formation whether they are oriented in normal relation with the wellbore or extend upwardly or downwardly into the formation in relation to their intersection with or extension from the wellbore. The term “fluid” as used herein is intended to mean any liquid, vapor, steam, gas, chemical leaching agent or combination thereof that causes liberation of heavy oil or a mineral from a subsurface formation as a production fluid and prepares or stimulates it for transportation to the surface.
For the production of fluid, such as crude oil or minerals from wells intersecting subsurface production formations, the formation of multilateral passages from a main or principal, typically vertical wellbore has been accomplished by rotary drilling or reaming as set forth in U.S. Pat. Nos. 4,880,067, 4,928,767 and RE. 33,660 of Jelsma, or by hydraulic jet blasting or drilling as set forth in U.S. Pat. Nos. 5,853,056 and 6,125,949 of Landers and U.S. Pat. Nos. 6,263,948 and 6,668,948 of Buckman et al. Other related inventions from the standpoint of radial or lateral formation of passages extending from a primary well are presented by U.S. Pat. Nos. 4,497,381, 4,527,639 and 4,787,465 of Dickenson et al, U.S. Pat. Nos. 4,640,362, 4,765,173 and 4,790,384 of Schellstede et al